Formings, such as trays and containers, prepared from sheeting of foamed thermoplastic resins, such as foamed polystyrene and foamed polyolefin, are used widely and in large quantities for vegetables, meat, fishes or cooked foods for their low cost and whiteness giving a clean feeling.
In recent years, weight has been given to recycling of these formings from the viewpoint of reduction of refuse and resource saving. However, the inside surface of formings collected after use are dirty and cannot be reclaimed as such. Besides, trays or containers for perishables such as raw noodles and hams are usually prepared from laminate sheeting composed of an foamed resin sheet and a gas barrier film in order to keep freshness. Such a laminate sheet composed of different materials should be separated into each material before reclaiming. For these reasons, recycling of used formings has been difficult.
In order to facilitate recycling of the formings, it has been proposed to laminate a film on sheeting so that the film can be stripped off the used formings without cleaning the inside surface of the formings, as disclosed in JP-A-U-4-38942 (the term "JP-A-U" as used herein means an "unexamined published Japanese utility model application") and Japanese Utility Model Application Nos. 16214/91 and 74081/92. According to the proposals, a strippable film is laminated or a foamed resin sheet with an adhesive, etc.
However, the strippable film of the individual formings proposed shows a large scatter in peeling strength, that is, the adhesive strength varies depending on parts. As a result, where a small strength thin film is used, it tends to be torn during stripping. If the adhesion is weak, the film is liable to be separated during use. If the adhesion is strong, the film cannot be stripped off easily.